This invention relates to a peristaltic diaphragm pump and more particularly to such a peristaltic diaphragm pump having nutating members which act upon a tubular diaphragm to provide a continuous sealing and flow of fluid.
Peristaltic diaphragm pumps and their advantages over pumps of the ordinary kind with a cylinder and a piston have been described, for example, in U.S. Pat. Nos. 3,058,428, 3,669,578, 3,922,119 and 4,483,666. Prior art peristaltic diaphragm pumps disclosed in these patents generally comprise a tubular member which spirals radially in the form of a nearly complete circle sandwiched between a stationary surface and a nutating surface so as to be peristaltically compressed therebetween along a radial sealing line. Since the tubular member through which a liquid is pumped does not form a complete circle, however, there is a loss of internal pressure every time the radial sealing line passes the direction in which the circle is not complete. Another disadvantage of prior art pumps of this type relates to their inability to handle foreign matter in the fluid without damage to the diaphragm or loss of pressure therein.